In Search of the Lost Interaction: A Theoretical and Methodological Framework for Researching Interactions

Area of Science:

• Psychology
• Statistics
• Research Methodology

Background:

• Investigating interaction effects in psychological research is complex.
• Current methods may not adequately address the nuances of interactional hypotheses.
• A need exists for a framework to guide the planning and interpretation of interaction studies.

Purpose of the Study:

• To propose a novel framework for analyzing psychological interaction effects using Positive Predictive Value (PPV).
• To structure potential interaction effects based on theoretical plausibility and shape.
• To inform sample-size planning, alpha level selection, and confidence in results.

Main Methods:

• Utilizing the Positive Predictive Value (PPV) framework.
• Defining PPV as the post-study probability of a true effect, considering pre-study probability (R), statistical power, and significance level (α).
• Developing a heuristic approach for planning interaction research based on R, PPV, and α.

Main Results:

• A proposed framework categorizes interaction effects by plausibility and shape.
• The framework provides guidance for pre-study planning (sample size, alpha) and post-study interpretation.
• A heuristic approach is presented to aid researchers in designing interaction studies.

Conclusions:

• The PPV framework offers a nuanced perspective on the feasibility of investigating interactional hypotheses.
• This approach balances critical assessment with encouragement for continued research on interactions.
• The proposed methods can enhance the rigor and interpretability of psychological interaction research.